Compressor



AW@ 9, i929., H. B, HALVORSEN Lmiz COMPRESSOR Filed April 5, 1924 compressor to prevent excessive temperatures' Patented Apr.. 9, 1929.

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1I COMPANY, COORIATION OF MASSACHUSETTS.

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Application :tiled April. 3,

My invention relates to compressors,` and more particularly to compressor unloading means.

An object of my invention is to provide an improved unloading means especially adapted to use with the high pressure cylinders o compressors. Another object ofthe present invention is to provide very simple and eiiicient unload-ing means which may be attached to one of the higher stages of a multi-stage in this stage when the inletto oneof the lower stages is vwholly or partially closed. These and other objects and advantages lof my invention will hereinafter more fully f Y sure cylinder from the low pressure cylinder I appear.

In the accompanying drawings l have sh vn for purposes of illustration one form 'which my invention may assume in practice.

In these drawings, Fig. 1 is a central vertical section through an illustrative embodiment of my invention.

Fig. 2 is a detailed sectional view, taken substantially on line 2 2 of Fig. 3'.

Fig. 3 is a plan Vview of the mechanism shown in Fig. l.

Fig. 4 is a view showing this improved unloading means turned through 90 and appliedto the side ofthehigh pressure cylinder of a compressor.

It is a well-known fact that if the intake' controlling valve of a compound compressor be closed for the purpose of unloading such a compressor, the continued reciprocation of the piston inthe high pressure cylinder will speedily pump down'the pressure in the intercooler to a. artial vacuum.with the result that any lea age which may occur past the intake closure valve will admit air to the com.- pressor which must be compressed in the high pressure cylinder from a pressure'substan-v tially subfatmosphericup to the :tull` discharge pressure of the high pressure cylinder. As a result of thisfact there will be a considerably larger number ofcompressions of the air in this cylinderthan is the case during normal running'and diie to the number of compressions aitemperature which may reach `or ,pass 500 degrees Fahrenheit will ,be produced. This of course is not desirable as it is apt tovcarbonizethe lubricant 'and in the event thatan explosive mixture 'of finely divided lubricant and air is present in the com- A pressor an explosion is-likely to result.l Variv ous means have been provided for preventing 1924. Serial No. 703,970.

the compression of air to the normal diS- charge pressure by permitting it to'be diS-V charged to the atmosphere as soon as a pressure somewhat'above atmospheric is reached v while the compressor is unloaded. My invenf tion herein consists of improved means for as soon as a pressure alittle above atmos- Y part 1 there extend from opposite sides pipe Y lines 2 and 3, these` being adapted to be connected to the counterbores fat' the vopposite ends of a high pressure cylinder HV (see Fig.

'4). The pipes 2 and '3 open into chambers 4 and 5 which are arranged at opposite sides of a' chamber 6 which opens into 'another chamber 7 which in turn is connected by a series of ports 8 controlled by a thin annular valve 9 with a recess 10 formed in a cap memtoythe atmosphere. vA transversely'bowed flexible spring 13 is held in pl'ace by. ama-- ber llthrough which an opening 12 extend-S` 'chine screw l 14 which servesv to maintain tlie valve 9 normally closed but permits it to open when thepressure inthe chamberv 7 is vsuhstantially .aboveatmospheric pressure. 'Bei- I tween the chambers 4 and Grand 5 and 6 there are arranged respectively valve seatsland 16, which are mutually-coaxial and which are adapted to provide `seats for apair of co.

axially arranged valves- 17 and 18 which are connected by 'a stem portion 19 andvmounted upon the up er end of a rod 20. In the lower portion oft e casing C which'is designated l 21-there is formed a cylinder ore 22 in which a piston 23 is reciproc'ableyt is piston being adapted to engage thebottom o the rod 2() and to forcethe valves 17 and 18 'to 'their seats. The piston is normally held in raised position by a spring 24 which engages the piston within a bore 25 in the latter at its v upper'end while its lower end cooperates with a follower 26 which may be adjusted by an adjusting screw 27 in the lower head 28 of the cylinder member 21. It will be observed that a counterborc 29 is arranged at the upper end of the cylinder and that the length of the rod 2O is such that it is impossible for the piston to Contact with the upper end of the cylinder when the valves are seated. 'A passage 30 serves to constantly vent the space'above the piston 23 lto the chamber 7 with the result that no pressure leaking around the rod' 20 can build up to oppose the upwardly acting .pressure below the piston 23. This might obviously leadl directly to the atmosphere. The

position of the piston 23 could be controlled by intercooler pressure if desired by connecting to an opening 31, which is herein closed by a plug 32, a line leading to the intercooler. However, this method is not employed and instead a connection 35 with the .bottom of the cylinder opens intb 4a passage' 36 and means is provided forcontrolling the pressure below the piston by the conditions in the opposite ends ofthe compressor cylinder. At its end away from the cylinder the passage 36 is branched as indicated at 37 and from the opposite ends of this branch there extend passages 38 and 39 parallel. to the passage ..36 and respectively surrounded by valve seats 40 and 41. Passages 37 and 38 lead'respectivelyto thechambers 4 and 5 which in l turn are connected Irespectively with oppothese valves, or fine bypasses extending site endsof the compressor cylinder by pipes 2 and-3. With these valve seats Valves 42 f and 43are adapted to cooperate, these valves being of thin sheet material and so formed by means of projections 44 at their peripheries as to be properly centeredwhile still permitting air to pass them when they are open. Suitable springs 45 and 46 arranged in chambers 47 and 448 containing these valves normally maintain them closed. It will be evident that vif it is necessary for pressure to build up beneath the piston 23when the com pressor is loaded in order that the valve 17 may be maintained closed, there must be some means whereby the pressure in the counterbores of the cylinder may pass the valves 42 and 43 toward the cylinder 22. For the accomplishment of? this result reliance may -be placed upon the .lack of perfect seating of around the valves may be used, or the valves may be drilled with small holes to permit the l through them,- thesel holes pressure to pass being of such size-as` not Vto interfere with the operation of these valves during unloaded operatiombut sufficiently large to allow pressure to pass through the valves in sufficient .quantities when the compressor is running loaded... f From the description so far given the mode of operation of this mechanism will be readily.

apparent.v Let it be assumed that ythe compressor is running loaded. It will then .be observed that the intercooler pressure which formsv without departingA may be, say, 25 or 30 pounds, ,is acting beneath the piston 23. If we assume that this piston has an area of, say, 3 square-inches, there would be an upward pressure of to 90 pounds. If we'assume that the area of the valve 17 lexposed topressure in the chamber 4 is one-half a square inch and that the maxi-y which might tend to unseat the lvalve 17 will be entirely insuflicient to accomplish this result and that during normal running of the compressor'both lthe bypass 'and the atmospheric vent will be completelyc losed off from' the opposite ends of the cylinder. Of course when the maximumprcssure is in the` end of the cylinder connected with the space 5, this will simply result in the-valve seating'more' tightly. Now, if the compressor be unloaded by theclosureof the intake closure valve there.

will be developed inthe intercooler after a few revolutions a partial vacuum and in like manner within the ends of the high pressure cylinder there would'be reduced pressures produced. During these periods of sub-atmospheric pressure 4the valves and 43 will be unseated by .the pressure below the piston 23l and the latter will be allowed to. be moved downwardly by the pressure acting upon the top of the piston through' the .opening 30. .This will permit the by ass Valve to drop open and, as the-re is` an un alanced area upon the valves 17 18, etc., tending to keep' them open, they will be `maintained open throughout the continuing un loaded running ofthe compressor. will therefore be no substantial compression in the high pressure cylinder for the fluid will .pump back and forth from end 'to end of the latter. In case' the 'leakage past the `intake closure yalve is such as to build up the high pressure cylinder and will pass out past the valve 9 to the atmosphere.

There While I have in this application specifically described one form which vmy invention mayl assume'in practice,it will be understood that .this form of the same is'shownfor purposes y of. illustration and that the lnventionmay be modified land embediedin various `other the scope of the appended claims. A f'.

- What I'claim as new and desireto-secure by Letters Patent is: '4

1. In an unloading mechanism, a casing providing chambers. connected directly with froml its spiritV orI .A moar-fra the opposite ends of the compressor-cylinder and an intermediate chamber, interconnected.: valves adapted to control the communication between said rst mentioned chambers and said last mentioned chamber, and means for Y controllingv the operation of said valves responsive to a vacuum condition in the compress'or cylinder proper for causing said valves tol interconnect the opposite ends of the cylinder.

2. A compressor controlling valve medh-'- cylinder, and means for normally holding said valves seatedincluding a spring pressed piston exposed on its side away from said valves to pressure in the cylinder proper.

3. A compressor controllingv valve mechanism comprising a casing containing a chamber having walls formed to present alined valve seats, interconnected valves cooperat- -ingwith said seats, means for subjecting said Avalves on their respective opposite sides .to

pressures in the opposite ends of a compressor cylinder, and means for normally holding said valves seated including a spring pressed piston exposed on its 'sideaway from said valves to pressure in the cylinder proper, the opposite end of said piston being vented to prevent the accumulation of pressure to act thereon.`

4. Ina mechanism'for eEecting unloading of a high pressure compressor cylinder, a cylmder, a plston thereln, means for connect:

f ing one end of said cylinder with both ends of such a high pressure cylinder, and valve means whose position is controlled by ,said

piston for controlling interconnection between the ends ofthe high pressure. cylinder. 5. Means for interconnecting the opposite ends of a high pressure compressor cylinder when said compressor is unloaded including two coaxial interconnected valves each controlling the connection between one end of the cylinder and the vspace between the l' valves, and means responsive directly to the pressure in the high pressure cylinder proper for controlling said valves. Y

6. In a compressor unloading mechanism, a casingincluding three alined chambers 'and a cylinder, connections between two of said chambers and the lends of a-compressor cylinder, means controlling the connections be-l tween said last mentioned chambers, and the -third chamber, and 'al single piston'in said' cylinder controlled by the pressuresin saidcylinder and controlling said'A controlling means. Y

y7. In a'fcompressor unloading mechanism,-

.a casing including three alinedchambers and a cylinder, connections between two of `said. chambers and the ends ofa compressor 'of said chambersand the atmosphere, meanscontrolling the connections between saidseveral chambers', and a single piston in said cylinder controlled by the pressures in the opposite ends of'said cylinder and controlling said controlling means.

' 9.- In a compressor unloading mechanism,

a casing incl'uding'three alined chambers. and a cylinder, connections between two of said chambers and the ends of'a compressor cylinder,'a valved connection between the third of said chambers and the atmosphere, means controlling the connections between said several chambers, and a single piston in' said cylinder controlled by' the pressures in thel opposite ends ofsaid cylinder and controlling said controlling means, one end of said cylinder being connected to said third chamber and the other having'check valved connectionswith the ends of a compressor cylinder.

10. An unloading mechanism adapted for connection to a compressor cylinder, said mechanism having two passages, one connected to each end oi the cylinder, and comprising valve means movable as a 'unitto interconnect the ends of the compressor cylinder, and means directly controlled by the cylinder pressure for controlling saidvalve means.

11. An unloading mechanism adapted for connection to a compressor cylinder, said mechanism having two passages, one connectved to veach vend of the cylinder `and comprisingvvalve means for controlling tluidflow through said passages and operative in one position to open communication between the `ends of the cylinder through said passages,

and means for'operating' saidA valve means, said operating means including achamber with connections between the same and the two ends of the cylinder and a check valve in each connection for preventing back low of fluid to said chamberfrom the compressor cylinder whereby said operating means is responsive to minimum pressure in the cylinp der ends.

12. Means or-interconnectingthe opposite -ends of a high pressure 'compressor cylinder' when said .compressor is unloaded' including means providing a chamber and connections between both ends of' such a high pressure cylinder'and said chamber, a member movable in response to the pressure within said cylinder, and valve means operated by said member for controlhng 1nterc0nneet1on between the ends of the high pressure cylinderY der of an air compressor comprising a casing communicating directly with the opposite ends ot such a cyhnder, interconnected Valve 10 means in said 'casing for opening communica# tion throughthelatter between the ends of said cylinder and normally held in a position to interrupt communication between the ends of the compressor cylinder, and means responsive to a vacuum condition in the cylinder for releasing said valve means to permit the opening of such communication.

In testimony whereof I affix `my signature.

HALBERT B. HALVoRsEN. 

